The present disclosure relates valve devices and methods for the prevention of bile reflux for bariatric stents.
Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy and/or increased health problems. Body mass index (BMI), a measurement which compares weight and height, defines people as overweight (pre-obese) when their BMI is between 25 kg/m2 and 30 kg/m2, and obese when it is greater than 30 kg/m2. Obesity is most commonly caused by a combination of excessive dietary calories, lack of physical activity, and genetic susceptibility. On average, obesity reduces life expectancy by six to seven years. Obesity increases the likelihood of various diseases, particularly heart disease, type 2 diabetes, breathing difficulties during sleep, certain types of cancer, and osteoarthritis. Obesity is the second leading preventable cause of death worldwide, with increasing prevalence in adults and children, and authorities view it as one of the most serious public health problems of the 21st century. The WHO estimated in 2005 that at least 400 million adults (9.8%) worldwide were obese. According to a CDC report, 34% of adults and 17% of children in the United States were obese in 2007-2008. Obesity has been estimated to cause up to 365,000 deaths per year in the United States.
Bariatric (or weight loss) surgeries are surgical treatments for treating severe obesity (BMI greater than 40 kg/m2 or BMI greater than 35 kg/m2) with a comorbidity. The most common bariatric surgery is Roux-en-Y Gastric Bypass (RYGBP) (FIG. 1), in which a small gastric pouch and an alimentary limb (Roux limb) are created and anastomosed to one another and to the patient's jejunum, bypassing part of the small intestine. Other bariatric surgeries, as shown in FIG. 2, may involve removal of a portion of the stomach (sleeve gastrectomy or biliopancreatic diversion with duodenal switch or biliopancreatic diversion with duodenal switch). In biliopancreatic diversion with duodenal switch, about 80 percent of the stomach is removed, forming a thin sleeve-like stomach. The valve that releases food to the small intestine remains (pylorus) along with a limited portion of the small intestine that normally connects to the stomach (duodenum). The surgery bypasses the majority of the intestine by connecting the end portion of the intestine to the duodenum near the stomach (biliopancreatic diversion). This weight-loss surgery is effective but has more risks, such as malnutrition and vitamin deficiencies, and requires close monitoring. It is generally used for people who have a body mass index greater than 50 kg/m2. About 150,000 patients undergo bariatric surgery each year. Long-term studies show the procedures cause significant long-term loss of weight, recovery from diabetes, improvement in cardiovascular risk factors, and a reduction in mortality of 23% to 40%.
It is reported that post-operative leaks occur in about 2% to 3% of bariatric surgery cases, but the real number may be higher due to underreporting. For RYGBP, leaks mostly occur along the stapling line of the gastric pouch and at the gastrojejunal anastomosis. However, leaks can also occur along the Z line between the esophagus and the stomach. Leaks are one of the most dreaded complications after bariatric surgery and are associated with increased morbidity and mortality. Leaks can be treated with several modalities, including site drainage with parenteral nutrition and bowel rest, various endoscopic methods (esophageal stents, clips, glue, sutures), and a second bariatric surgery. These treatment modalities all have drawbacks.
Esophageal stents have been successfully used to treat leaks after sleeve gastrectomy or biliopancreatic diversion with duodenal switch. These stents are prone to migration, however, because their shape is not adapted to the modified stomach geometry after sleeve gastrectomy or biliopancreatic diversion with duodenal switch. Two stents are often employed because existing stents are simply too short for a successful treatment.
For sleeve gastrectomy or biliopancreatic diversion with duodenal switch, most of the leaks occur in the upper part (the proximal third) of the sleeve. This occurs because the upper part is less accessible during surgery and more difficult to staple.
In a majority of cases where leakage occurs, there is a stricture in the incisura region of the stomach that creates an increase in pressure in the upper part of the sleeve. FIG. 3 is included as a representation of the stomach geometry prior to sleeve gastrectomy or biliopancreatic diversion with duodenal switch and FIG. 4 is included as a representation of the stomach geometry after sleeve gastrectomy or biliopancreatic diversion with duodenal switch.